1. Field of the Invention
The invention relates to a method for monitoring the refrigerant filling level in a refrigerating system, and more particularly to a method for monitoring the refrigerant level in an air conditioner having a compressor with a high pressure refrigerant circuit and a low pressure refrigerant circuit.
2. Description of the Related Art
DE 44 01 415 C1 describes a generic method for monitoring the refrigerant filling level in a refrigerating system, the refrigerating system having a compressor subdividing the refrigerant circuit into a high-pressure side and a low-pressure side. The relative pressure and the temperature are measured on the high-pressure side at time intervals, the measured pressure is used to determine an assigned temperature by means of a refrigerant-specific function and a refrigerant subcooling value Uw capable of being evaluated as a measure of the refrigerant filling level is determined by subtracting the measured temperature from the assigned temperature. At least during predeterminable operating phases of the refrigerating system, a maximum value Mw is used to assess the refrigerant filling level, and at the start of these operating phases, this maximum value is set at the subcooling value Uw last determined and, in the course of this operating phase, at a subcooling value newly determined in each case, when the latter is higher than the maximum value Mw prevailing at the corresponding time.
This type of method for monitoring the refrigerant filling level in a refrigerating system has the disadvantage that a refrigerant temperature sensor is required in the system in order to record the refrigerant temperature.
The present invention is aimed at one or more of the problems identified above.
The object of the invention is to improve a method for monitoring the refrigerant filling level in a refrigerating system, in such a way that the need for costly sensor technology can be avoided.
The object is achieved, according to the invention, by means of the features of Claim 1. Advantageous refinements and developments of the subject of the invention are characterized by the features of the subclaims.
An essential advantage of these refinements is that, merely by observing the evaporator temperature already measured for other purposes, the filling level of the refrigerant can be monitored and, if there is an underfilling of refrigerant, the compressor can be switched off for protection.